Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.

Hi,converting a PDF (consisting of 441 pages) to PNG works in a few seconds on an old Linux machine but takes about 15 minutes (!) on a new Windows machine. The CPU load on Windows is 100% during the conversion, in the first seconds the memory usage jumps from 700MB to 2GB (=100% = 1GB real memory + 1GB virtual memory). What is the reason for that slow speed on Windows? Though loading+displaying that PDF file in Adobe Reader just takes 2 seconds. The PDF (2.15MB) is here: http://www.engr.uconn.edu/~zshi/course/ ... _guide.pdf

To answer your question you would need to add '-debug cache' to your command line and post the output of both Windows and Linux. The debugging output would shed light onto any slowdown you're seeing under Windows.

ImageMagick leverages Ghostscript to render the Postscript pages. On your system it takes 3 minutes. On our Linux-based system, the same conversion takes 1 and a half minutes. The remaining time is consumed by compressing the images and saving them in the PNG format.

We have the same processor on our Linux host. Your document converts for us in just over 2 minutes. If you don't have transparent PDF pages, you can edit delegates.xml and change the pngalpha device to pnmraw. That reduced the run time to 1 and 1/2 minutes.

For your conversion, you probably will want to bypass ImageMagick and use Ghostscript directly from the command line. That will reduce the run-time to just over 3 minutes on your Windows box.

Firstly, I just wanted to find out where all the time is spent on conversion of my special 441 pages example PDF file spru198j_programmers_guide.pdf. Understanding could help to find the reason of possible misconfiguration of my system. That's why I asked why IM's "Cache destroy" takes 3 minutes, what is happening there, internally; what could put a brake on that?

You say, for conversion from PDF to PNG, it's enough to just call GS. What command line call of GS would replace my "convert -debug cache -limit area 0 spru198j_programmers_guide.pdf test.png"?

Add -verbose to your command line and it displays the Ghostscript command line.

Your system is not mis-configured. ImageMagick traditionally has been much speedier on Linux than Windows. Note, its the same code base between the two machines so any slowness lies directly with the Windows OS or perhaps the standard C library compatibility layer Microsoft provides.

441 pages in 900 seconds, this is a speed of 2 seconds per page on a 2,5MB PDF document, it would be silly to blame Windows for that on a today's machine. Again, what are you doing for instance in that 3 first minutes of logged action "Cache destroy"?

magick wrote:For your conversion, you probably will want to bypass ImageMagick and use Ghostscript directly from the command line. That will reduce the run-time to just over 3 minutes on your Windows box.

Sorry, I cannot see from the -verbose output (see below) what I should use as command line call to Ghostscript to convert from my PDF to those 441 PNGs.